Date of Award

Fall 2015

Degree Type


Degree Name

MS Industrial Hygiene


Industrial Hygiene

Committee Chair

Theresa Stack

First Advisor

Sally Bardsley

Second Advisor

Andy O'Brien

Third Advisor

Janet Richards Coe


Since 2000, the Mine Safety and Health Administration (MSHA) has reported 737 injuries involving bagging. Most of these injuries were related to “over-exertion” with an MSHA injury classification of “strains, sprains, and ruptured discs.” “Over-exertion” accounted for 331,130 injuries totaling 14.2 billion dollars in workers compensation costs in 2012 according to the National Safety Council (NSC). According to NSC, the average total incurred cost of an “over-exertion” injury is $42,883/claim, and the average total incurred cost of a “strain/sprain” injury is $31,521/claim.

Manual bagging in a sand mine processing plant is a highly physical job. There are six physical workplace risk factors associated with the development of work-related musculoskeletal disorders (WMSDs); posture, compression, force, repetition, vibration, and duration. These must occur in some combination to cause WMSDs. Manual bagging risk factors include posture, compression, force, repetition, and duration. Despite all of these risk factors, implementing an automated bagging system is an expensive capital project that is generally difficult to justify for most companies.

The objectives of this research are to determine if implementing an automated bagging system will not only decrease exposures to physical work place risk factors (ergonomic hazards), but also decrease exposures to noise, respirable dust and respirable crystalline silica, as justification for the cost of such a system. Additionally, the research is investigating if there is a reduction in injuries and workers compensation costs to a plant that implements an automated system.

Ergonomic evaluations were performed on nine employees with the job description of “bagger” at four industrial mineral mine processing plant locations in the United States. Ergonomic analyses were performed using the NIOSH “Ergonomics Audits for Mining Bagging, Haul Truck, and Maintenance and Repair Operations” Auditing Tool and the Rapid Upper Limb Assessment (RULA) for the job sub-task of tying bulk-bags.

A nonparametric Wilcoxon sum-rank test was performed on the dust and noise data using SAS software considering exposures before and after the implementation of a fully automated bagging system.

The statistical analysis showed a statistically significant reduction in the noise exposures, however there was not a statistically significant reduction in the respirable dust or respirable crystalline silica exposures. The ergonomic hazards associated with manual bagging are numerous and have far reaching potential in regards to the risk of injury. Almost all of the risk factors associated with workplace musculoskeletal disorders are associated with manual bagging. The implementation of a completely automated bagging system would all but eliminate the ergonomic exposures. The yearly adjusted injury rate dropped from 2.76 per year to 0.72 per year after the implementation of an automated system in Plant A. Also, the estimated reduction in workers compensation claims is approximately $34,000 with a return on investment potential of less than 6 years on the conservative side.

Based on the ergonomic evaluation of manual bagging as well as the positive reduction in noise exposure it is safe to say that automated bagging systems are worth the upfront costs if they only prevent even one injury a year.


A thesis submitted in partial fulfillment of the requirements for the degree of Masters of Science in Industrial Hygiene Montana Tech 2015